code: def test_empty_layers(self):
      input_spec = tensor_spec.TensorSpec((2, 3), tf.float32)
      network = encoding_network.EncodingNetwork(
          input_spec,
      )
  
      # Only one layer to flatten input.
      self.assertLen(network.layers, 1)
      config = network.layers[0].get_config()
      self.assertEqual("flatten", config["name"])
  
      out, _ = network(tf.ones((1, 2, 3)))
      self.assertAllEqual(out, [[1, 1, 1, 1, 1, 1]])
      self.assertEmpty(network.variables)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl.testing import parameterized
  import numpy
  import tensorflow
  from tf_agents.networks import encoding_network
  from tf_agents.specs import tensor_spec
  from tf_agents.utils import test_utils
label_desc: Use image node_id 1 for calling the EncodingNetworkTest obj's underlying member method code with example usage: obj.test_empty_layers() without return types